Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Biochemistry > Metabolism Of Kidney > Flashcards

Metabolism Of Kidney Flashcards

1
Q

Blood supply differences in kidney

A

. 90-95% of renal blood passes through cortex and uses 8% of oxygen in blood
. 5-10% of renal blood passes through medulla and uses 80% of oxygen in that blood
. Medulla more vulnerable to anoxic shock

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Roles of kidney

A

. Makes urine to excrete waste, regulate serum pH, electrolytes, and water
. Has enzymes for gluconeogenesis
. Acts as endocrine gland: synthesizes and releases EPO, renin
. Contains enzymes for vit. D metabolism important for serum Ca, ,phosphate, and bone metabolism regulation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Components of urine synthesis

A

. Filtration
. Reabsorption
. Secretion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Sequence of events in filtration

A

. Blood enters afferent arterioles
. GFR depends on bp
. Filters through 3 layers
. Capillary endothelium: 100x more permeable than other capillaries
. Basement membrane: composed of highly negatively charged glycoproteins and proteoglycans
. Single layer of epithelial cells (podocytes) w/ foot processes that interdigitate w/ one another

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What gets filtered in kidney?

A

. 20% plasma volume through kidney forced through filter to become ultrafiltrate
. Collects in Bowman’s capsule

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Ultrafiltrate contents

A

. Plasma H2O

. Small solutes (glucose, NaCl, urea, AA)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Ultrafiltrate does NOT contain _____

A

. Cells or cell-like structure

. Proteins beyond a certain limit ( larger and neg. charges proteins do NOT go through)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Glomerular filtration rate

A

. Measured by injecting radioactive substance that’s filtered in kidney and not reabsorbed by tubules
. Takes blood samples over several hours
. dec. GFR is sign of diminished kidney function

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Reabsorption in kidney

A

. Movement of material from tubule lumen into capillary
. Much if what is filtered is reabsorbed
. Requires energy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Secretion in kidney

A

. Movement of material from capillaries into tubule lumen

. Requires energy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Modes of transport in kidney tubules

A

. Primary active transport (NA-K-ATPase)
. Secondary active transport (glucose/Na cotransport and amino acid-Na cotransport)
. Pinocytosis and endocytosis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Important indicators of renal function

A

Levels of urea and creatinine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Azotemia

A

. Asymptomatic

. Nitrogenous waste products that accumulate in patient’s serum

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Uremia

A

. Symptomatic (nausea and vomiting) nitrogenous waste product build up in patient’s serum

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Renal threshold

A

. Substance that are absorbed have limit to rate at which solute can be transported
. When limit is surpassed the excess is secreted
. Glucose threshold is 220 mg/dl

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Endogenous compounds secreted by tubules in kidney

A

. Urate, creatinine, bile acid salts

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Exogenous compounds secreted in kidney tubules

A

. Penicillin

. Salicylate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What determines final composition of urine?

A

. Excretion = filtration-absorption+secretion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

PH of urine is between _____

A

4.4 and 8

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Reabsorption of bicarbonate

A

. Most passes through filter and is reabsorbed by transporters in tubule cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Kidney excretion of phosphate and other acids

A

. Molecules that have pK in range of pH of urine can pick up proton and carry out in urine
. Occurs w/ any acid that can bind H and carry it out in urine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What happens in kidneys during diabetic ketoacidosis

A

. Inc. of ketones
. Compounds filtered and appear in tubule fluid
. As urine pH dec., these compounds begin to serve as buffers that can carry H out of body in urine

23
Q

Excretion of ammonia/ammonium

A

. NH4 is major urinary acid (1/2-2/3 daily acid load excreted w/ this)
. Preserves Na and K reserves in prolonged acidosis (other acids need this)

24
Q

Aerobic vs. anaerobic metabolism in kidney

A

. Uses 10% of O2 the body uses
. Renal cortex more highly oxidative then medulla
. Medulla depends on glycolysis and is sensitive to low [O2]

25
Q

Glucose utilized in renal medulla is produced in ___

A

Renal cortex

26
Q

Major renal fuel used in normal (fed) person

A

Lactate (45%)

27
Q

Major renal fuel in acidosis

A

Glutamine

28
Q

Major renal fuel in a fasted state

A

. Fatty acids

29
Q

Gluconeogenesis in kidney

A

. Can make 20-50% as much glucose as liver
. Predominantly associated w/ cortex
. Cortex is highly oxidative tissue w/ high ATP synthetic ability
. Substrates: Gln, lactate, citrate, alpha-ketoglutarate
. Important in starvation and acidosis

30
Q

If acidosis is treated w/ alkali administration, then renal gluconeogenesis is___

A

Not stimulated

31
Q

Non-excretory mechanism for kidney pH regulation

A

. Conversion of certain organic acids to glucose

32
Q

Glutamine in kidney

A

. Gln taken up from blood

. Renal uptake regulated by pH (inc. uptake w/ acidosis) and glucocorticoids (stimulate glutaminase and Gln metabolism)

33
Q

Glutamine metabolism in kidney

A

. Glutaminase converts Gln to Glu and releases 2 NH3 molecules for H excretion
. Glutamate dehydrogenase converts Glu to alpha-ketoglutarate that can be used in ATP or as substrate for gluconeogenesis

34
Q

Erythropoietin

A

. Polypeptide hormone
. Synthesized in response to reduction in renal PO2
. Stimulates bone marrow to inc. production of erythrocytes

35
Q

People w. Impaired renal function and anemia are given ___

A

Exogenous EPO

36
Q

Renin

A

. Protease
. Made in response to signals from granular cells that ac as intrarenal baroreceptors
. When pressure drops the synthesis of renin is stimulated

37
Q

Renin-angiotensin system

A

. Angiotensinogen (plasma protein in liver) gets cleaved to angiotensin I through renin
. angiotensin I is converted to angiotensin II via angiotensin-converting enzyme (ACE)

38
Q

Rate limiting step in RAAS

A

Renin

39
Q

Where does RAAS occur?

A

. Exists in plasma and vascular surface of blood vessels throughout body, esp. in kidneys

40
Q

Angiotensin II functions

A

. Potent vasoconstrictor, inc. bp
. Inc. synthesis of aldosterone, steroid hormone, that inc. Na reabsorption
. Inhibits renin synthesis

41
Q

ACE inhibitors

A

. Captopril
. Benazepril
. Enalapril

42
Q

Angiotensin II receptor blockers

A

. Irbesartan
. Candesartan
. Losartan
. Valsartan

43
Q

Vitamin D

A

. Dietary or synthesized from cholesterol in skin
. Regulates serum Ca and phosphate
. Interacts w/ bone, kidney, and intestine
. Promotes absorption of Ca in intestine
. Liver converts it to circulating form of Vit D
Kidney converts it to active or inactive form

44
Q

Vitamin D deficiency

A

. Causes inability to absorb dietary Ca

. Results in bone loss

45
Q

Chronic renal failure in relation if vit. D

A

. Results in Inability to produce active vit D
. Bone Ca becomes depleted
. Inc. retention of Pi because kidney can’ excrete it causing high serum phosphate
. When Pi is hig, less Ca can remain in solution
. Leads to bone loss and soft tissue calcification
. Treatment: high Ca diet, vit. D supplements, Pi reduction w/ Pi binding antacids

46
Q

Symptoms associated w/ kidney failure

A 
. High bp
. Back pain just below rib cage 
. Frequent urination
. Rusty or brown colored Urine 
. Swelling edema of the feet and ankles
47
Q

Serum levels elevated in patients w/ kidney failure

A

. Urea
. Creatinine
. Uric acid

48
Q

Urinalysis of someone w/ chronic kidney disease

A

. GFR dec. w/ inc. damage
. Urinary protein inc.
. Urinary blood cells inc.
. Urine volume (too little not enough filtration, too much means inability to concentrate urine)

49
Q

Oliguria

A

Very little urine production

50
Q

Kidney not filling endocrine duties will cause ___

A

. Lack of EPO: low hematocrit, low rbcs, tiredness, malaise

. Lack of kidney function: hypertension

51
Q

Acute renal failure

A

. Rapid and usually reversible deterioration of renal function
. Pre-renal causes: blood loss, hemorrhage, CHF
. Renal causes: bacterial infections, intoxins, rhabdmyolysis
. Postrenal: cancer, obstruction of ureter

52
Q

Rhabdmyolysis

A

. Damage to skeletal muscle causing myoglobin release
. Appearance of myoglobin in blood and urine
. Myoglobin extremely damaging to kidneys
. Caused by: trauma, excessive exertion in heat, crush syndrome

53
Q

Chronic renal failure

A

. Slower, progressive, irreversible loss of renal function
. DM causes 40% cases, hypertension 20%
. 5 stages (1 being slight damage, 5 requiring dialysis or transplant)

Biochemistry (64 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions